Enzyme Immunoassay for the Quantitative Determination of Prolactin Concentration in Human Serum.
Introduction
Prolactin (PRL), also known as the lactogenic hormone, is secreted by the anterior pituitary gland in both men and women. It is a single-chain polypeptide hormone with a molecular weight of approximately 23,000 daltons. Prolactin secretion is regulated by neuroendocrine control, primarily through Prolactin Releasing Factor (PRF) and Prolactin Inhibiting Factor (PIF). Baseline prolactin levels are typically higher in women than in men, with a significant estrogen-related increase at puberty and a decrease at menopause (Seppälä, 1978).
Prolactin plays a crucial role in mammary gland development and lactation maintenance. Additionally, it inhibits gonadal function. During pregnancy, prolactin levels increase significantly—10 to 20 times the normal range—and return to non-pregnant levels within 3 to 4 weeks postpartum (Bergh et al., 1977). In lactating mothers, prolactin levels remain elevated for several months.Clinically, prolactin measurement is instrumental in diagnosing hypothalamic-pituitary disorders. Hyperprolactinemia is associated with conditions such as galactorrhea, amenorrhea, and infertility. It can be triggered by factors such as estrogen, thyrotropin-releasing hormone (TRH), and certain medications affecting dopaminergic pathways. Additionally, elevated prolactin levels may be observed in renal disease, hypothyroidism, stress, and hypoglycemia. Some medications, such as chlorpromazine and reserpine, increase prolactin levels, whereas bromocriptine and L-dopa decrease them (Thorner et al., 1974). Given its diurnal variation, mild elevations in prolactin concentrations should be interpreted cautiously.
Clinical Significance
The assessment of prolactin levels is critical in diagnosing and managing reproductive and endocrine disorders. Elevated prolactin levels are commonly seen in prolactinomas, the most frequent type of pituitary adenomas, leading to menstrual irregularities, infertility, and hypogonadism. Prolactin excess may also be associated with psychiatric conditions, renal failure, and hypothyroidism (Bergh et al., 1977). Conversely, reduced prolactin levels can impact lactation and reproductive function.
Measurement of prolactin levels assists in differentiating between pathological and physiological causes of hyperprolactinemia. In clinical practice, the PRL ELISA kit is a valuable tool for accurate and efficient prolactin quantification, aiding in patient diagnosis and management.
Principle of the Assay
The Prolactin ELISA Kit utilizes a solid-phase enzyme-linked immunosorbent assay (ELISA) technique. The system employs one anti-prolactin antibody immobilized on a microtiter plate and a second monoclonal anti-prolactin antibody conjugated to horseradish peroxidase (HRP). Following sample incubation, the sandwich complex is formed, and a chromogenic substrate reaction results in a color change, measured spectrophotometrically at 450 nm. The color intensity is directly proportional to the prolactin concentration in the sample.
References
- Bergh, T., Nillius, S. H., & Wide, L. (1977). Hyperprolactinemia in amenorrhea: Incidence and clinical significance. Acta Endocrinologica, 86(4), 683-694.
- Seppälä, M. (1978). Prolactin and female reproduction. Annals of Clinical Research, 10(3), 164-170.
- Thorner, M. O., McNeilly, A. S., & Hagan, C. (1974). Long-term treatment of galactorrhea and hypogonadism with bromocriptine. British Medical Journal, 2(5934), 4-7.